Research progress on the crystallization behavior of coal slag in entrained-flow gasifiers

LU Hao; BAI Jin; KONG Lingxue; GUO Zhenxing; LI Huaizhu; LI Wen

doi:10.13226/j.issn.1006-6772.XJ24012901

Abstract：Gasification is one of the important technologies to realize the transformation of coal from fuel to raw material and to promote the clean and efficient utilization of coal.Entrained-flow gasification is currently the predominate gasification technology,and the stable operation of gasifiers requires that the liquid slag must have good fluidity.The crystallization behavior of the slag can lead to decreased flowability,resulting in abnormal shutdown of the gasifier,which is a major cause of abnormal shutdowns of gasifiers.The main crystalliza-tion characteristics were summarized and discussed that affected the fluidity of slag and the key to studying crystallization behavior:crys-tallization kinetics.Firstly,the methods of judging the crystallization mechanism based on crystallization behavior and selecting appropri-ate crystallization kinetics models were summarized.The principles and characteristics of different crystallization detection methods were compared to obtain more accurate crystallization behavior data by selecting the appropriate crystallization behavior detection method according to the research focus,facility characteristics and slag properties.Finally,the effects of chemical composition and operating con-ditions on crystallization behavior were summarized.Significant differences in the crystallization mechanisms between different crys-tals cause that the same chemical composition has different effects on the crystallization behavior of different crystals.When the chemi-cal composition of the designated slag is within a specific phase region,the influence of chemical composition and operating conditions on crystallization behavior of the primary phase mineral becomes more regular,and the conclusions obtained can provide more accu-rate guidance for the regulation of crystallization behavior.Combining research results with phase diagrams or establishing simple and ac-cessible predictive models can better guide the control of slag crystallization behavior.Currently,the study of crystallization behavior main-ly relies on experimental methods.Future research could integrate phase-field simulation and molecular dynamics simulation,among oth-er methods,to further explore the mechanisms of crystallization and examine the effects of factors such as temperature fields and flow fields within gasifiers on crystallization characteristics.